/Engine/Source/Runtime/MeshDescription/Public/MeshDescription.h
Returns reference to an array of VertexInstance IDs forming the perimeter of this polygon
template<typename Alloc> void GetPolygonVertexInstances ( const [FPolygonID](API\Runtime\MeshDescription\FPolygonID) PolygonID, [TArray](API\Runtime\Core\Containers\TArray)< [FVertexInstanceID](API\Runtime\MeshDescription\FVertexInstanceID), Alloc > & OutVertexInstanceIDs ) const